1. The Field of the Invention
The present invention relates to tibial condylar hemiplasty implants, anchor assemblies used to secure such implants to the tibia, and the related methods.
2. The Relevant Technology
The knee joint comprises two generally rounded condyles, i.e., lateral and medial condyles, that are located at the lower or distal end of the femur. These femoral condyles are disposed above corresponding lateral and medial condyles located at the upper or proximal end of the tibia. A flexible meniscus provides cushioning between the opposing matching pairs of condyles.
As a result of injury, wear, disease or other causes, it is occasionally necessary to replace all or part of the knee joint. Knee replacements typically entail cutting off or resecting both of the femoral condyles and the tibial condyles. Complementary artificial implants are then mounted on the distal end of the femur and the proximal end of the tibia. Where only one condyle has been injured, more recent procedures provide for partial knee replacement. In this procedure, only one of the lateral or medial femoral condyles is resected. The corresponding one of the lateral or medial tibial condyles is also resected. Implants referred to as “unicondylar” implants are mounted on the resected area of the femur and tibia.
Although knee replacements have met with success, one of the significant drawbacks to knee replacements is the recovery. Traditional knee replacements, both full and partial, require an open procedure wherein relatively large incisions are made so as to fully expose the respective ends of the femur and tibia. This exposure is necessary when using conventional techniques to resect the femur and tibia and for mounting the implants. For example, conventional tibial implants are screwed directly into the resected end face of the tibia. Mounting such screws requires exposure of the resected end face. In yet other embodiments, projections are formed on the implants which are received within slots formed on the resected end face of the tibia. Again, forming of the slots and inserting the implant into the slots requires substantially full expose of the resected end face of the tibia.
In general, the more invasive the surgery, the more difficult and time consuming the patient recovery. Furthermore, such open and invasive surgeries have a greater risk of infection.
Accordingly, what is needed are systems and methods for resecting and mounting a condylar implant on the tibia that uses procedures that minimize incisions, the amount of bone resection, and/or the impact on soft tissue.